Prior to application or implantation medical tools must be sterilized. In order to reduce the risk of contamination the number of handling steps of sterilized products should be kept to a minimum. Therefore medical tools are often sterilized together with the housing in which they are delivered or stored. The housings should allow easy access of the sterilizing agent (vapour, liquid or radiation) to the product to be sterilized. Furthermore, the housing should protect the medical tool from physical damage. Some medical products are very sensitive to abrasion due to contact with other surfaces, especially in combination with vibration, which often occurs during transportation.
This is particularly true in relation to dental implants, which are inserted into the jaw bone to replace one or more teeth. The surface of these implants, particularly those parts of the implant which will, in use, be positioned within the bone, are often treated to enhance tissue adhesion. Such treated surfaces are very sensitive to abrasion or deterioration when placed in contact with other surfaces.
To minimize abrasion and other deteriorating interactions with any surface, housings have been developed in which the medical tools, such as implants, can be firmly attached to the body of the housing for transportation and storage. Housings are known which firmly hold the implant at specified areas in such a way that the majority of the implant is held away from the interior of the housing.
U.S. Pat. No. B1 6,261,097 discloses a housing including a holding device which comprises a sleeve and a carrier screw, one end of which can be screwed into the internally threaded bore of an implant. The sleeve of the holding device serves to fix the implant inside an ampoule such that the implant itself does not contact the ampoule walls. The opposing end of the screw is shaped for connection to a screwing-in, or insertion, tool for removal of the implant from the housing and implantation.
The sleeve is in contact with the body of the housing during transportation. Prior to insertion of the implant the carrier screw is connected to an insertion tool. The arrangement consisting of implant/sleeve/carrier screw/insertion tool is then removed from the housing. With the aid of the insertion tool the implant is then screwed into a cavity in the bone. The carrier screw therefore provides means to transmit torque from the insertion tool to the implant. After the implant has been screwed into the bone the carrier screw is detached from the implant. For this step the practitioner reverses the direction of rotation of the insertion tool.
A disadvantage of this system is that the carrier screw might not easily be removed from the implant as force is applied to the carrier screw during insertion of the implant, which connects the carrier screw tightly to the implant. Therefore, special care has to be taken when unscrewing the carrier screw from the implant not to loosen the connection of the implant to the bone. This requires the use of an additional tool to steady the implant during initial loosening of the carrier screw. The need to unscrew the carrier screw to remove the holding element presents an additional, undesirable step in the implantation procedure.
Furthermore, a holding piece comprising two components creates greater manufacturing costs and complexity.
HP-A1-1 749 501 describes a holding element for a dental implant including an engagement section for connection to an insertion tool, a retention section adapted for engagement with a housing and a clamping member for connecting the holding element to the dental implant. The clamping member lockingly engages the implant when the clamping member is in a non-compressed position. The holding element can thus be removed from the implant after insertion simply by compressing the clamping member without the need for an unscrewing motion. However the holding element must still be connected to a separate insertion tool in order to insert the implant. Therefore after insertion both the insertion tool and the holding piece must be removed from the implant.
The holding element further comprises a force transmission element, which co-operates with the internal structure of the implant in order to transmit a torque to the implant. The holding element must therefore be strong enough to withstand the torque placed on it during use and to transmit this effectively to the implant. Therefore the holding element is often made from titanium or another metal material via machining.
The cost of production of this type of holding element is therefore high. As the holding element is used to hold the implant within the packaging a separate holding element must be manufactured for each implant. This increases the cost of production of each implant.
Insertion tools which connect directly to the implant are also known. These can be multiple use tools which are provided to the surgery separately from the implant or single use tools supplied within the implant housing. Although this overcomes the problem of having two separate elements connected to the implant during insertion, the use of a directly connecting insertion tool results in new problems. When the insertion tool is provided in the packaging the above discussed problem of high manufacturing expense remains. When the tool is provided separately an alternative solution to the problem of securely holding the implant within the packaging must be found.